Phenotypic plasticity of polyploid plant species promotes transgressive behavior in their hybrids

Authors: GALLEGO-TEVAR, BLANCA - University Of Sevilla; RUBIO-CASAL, ALFREDO - University Of Sevilla; DE CIRES, ALFONSO - University Of Sevilla; FIGUEROA, ENRIQUE - University Of Sevilla; Grewell, Brenda; CASTILLO, JESUS - University Of Sevilla

Submitted to: AoB Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2018
Publication Date: 9/23/2018
Citation: Gallego-Tevar, B., Rubio-Casal, A., De Cires, A., Figueroa, E., Grewell, B.J., Castillo, J.M. 2018. Phenotypic plasticity of polyploid plant species promotes transgressive behavior in their hybrids. AoB Plants. 10(5):ply055. https://doi.org/10.1093/aobpla/ply055.
DOI: https://doi.org/10.1093/aobpla/ply055

Interpretive Summary: Following establishment and invasive spread of alien plant species, often hybridization between native congeners and the invaders is a secondary effect of invasion. The implications of these hybridization events for evolution and ecology of plant species and their impacts on recipient communities are not fully understood. Improved knowledge of how interspecific hybridization influences mechanistic traits with clear physiological functions that can drive evolutionary and ecological processes is needed to better understand invasions and their management. Hybridization between different plant species is a frequent process that leads to relevant evolutionary consequences associated with transgressive phenotypes and with high phenotypic plasticity, but there is a lack of studies regarding the relationships of the variability of the response of parental plant species to environmental gradients and the inheritance mechanisms at work in their hybrids. We designed an experiment in which invasive Spartina maritima x densiflora and S. densiflora x maritima hybrids and their parental species were exposed to four levels of aqueous salinity. The main objectives were to compare the performance of the hybrids with that of their parents, to distinguish the inheritance mechanisms operating in the hybrids, and to analyze the relationships between the variability in the responses of the parents and the responses of their hybrids. We characterized middle-term plant responses and the degree of variability for 37 foliar traits. Our results showed greater salinity tolerance of both Spartina hybrids than tolerance of their parental species. Both hybrids showed their highest percentage of transgressive traits at both extremes of the salinity gradient. When the parental plants themselves showed a more plastic response for a given trait, there was a greater chance that the hybrid develops a transgressive behavior for this trait.

Technical Abstract: Hybridization between different plant species is a frequent process that leads to relevant evolutionary consequences associated with transgressive phenotypes and with high phenotypic plasticity, but there is a lack of studies regarding the relationships of the variability of the response of parental plant species to environmental gradients and the inheritance mechanisms at work in their hybrids. We designed an experiment in which invasive Spartina maritima x densiflora and S. densiflora x maritima hybrids and their parental species were exposed to four levels of aqueous salinity. The main objectives were to compare the performance of the hybrids with that of their parents, to distinguish the inheritance mechanisms operating in the hybrids, and to analyze the relationships between the variability in the responses of the parents and the responses of their hybrids. We characterized middle-term plant responses and the degree of variability for 37 foliar traits. Our results showed greater salinity tolerance of both Spartina hybrids than tolerance of their parental species. Both hybrids showed their highest percentage of transgressive traits at both extremes of the salinity gradient. When the parental plants themselves showed a more plastic response for a given trait, there was a greater chance that the hybrid develops a transgressive behavior for this trait.